Mill unjamming device

ABSTRACT

I DISCLOSE AN UNJAMMING MECHANISM FOR ROOLING MILL SCREWDOWN MEANS AND THE LIKE, SAID MECHANISM COMPRISING A PAIR OF OPPOSITELY ROTATABLE SHAFT COUPLED TO SAID SCREWDOWN MEANS, SHAFT DISPLACING MEANS MOUNTED UPON EACH OF SAID SHAFTS FOR IMPARTING EQUAL AND OPPOSITE ANGULAR DISPLACEMENTS THERETO, AND MOTIVE MEANS COUPLED BETWEEN SAID SHAFT DISPLACING MEANS FOR ACTUATING SAID DISPLACING MEANS IN OPPOSITE DIRECTIONS.

Nov. 16, 1971 J. PROKELL MILL UNJAMMING DEVICE Filed May 16, 1969 4. Sheets-Sheet 1 L. I II P a #0 W5 MW Z n h Nov. 16, 1971 Filed May 16', 1969 J. -L. PROKELL MILL UNJAMMING DEVICE 4 Sheets-Sheet 2 Nov. 16,1971 J. L. PROKELL MILL UNJAMMING DEVICE 4 Sheets-Sheet 3 Filed May 16, 1969 LLIl HJL Nov. 16, 1971 J. L. PROKELL 3,620,052

MILL UNJAMMING DEVICE Filed May 16, 1969 4 Sheets-Sheet L .r/vmnrworr John L Praia 61.

BY I I 32 M45 4 H15 HYWOHA/EKS' United States Patent 3,620,062 MILL UNJAMMING DEVICE John L. Prokell, Bentleyville, Pa., assignor to Mesta Machine Company, Pittsburgh, Pa. Filed May 16, 1969, Ser. No. 825,318 Int. Cl. B2111 31/24 US. Cl. 72-248 17 Claims ABSTRACT OF THE DISCLOSURE I disclose an unjamming mechanism for rolling mill screwdown means and the like, said mechanism comprising a pair of oppositely rotatable shafts coupled to said screwdown means, shaft displacing means mounted upon each of said shafts for imparting equal and opposite angular displacements thereto, and motive means coupled between said shaft displacing means for actuating said displacing means in opposite directions.

The present invention relates to a rolling mill unjamming device and more particularly to a device of the character described coupled to the screwdown mechanism usually provided for a rolling mill stand. The screwdown mechanism includes in most cases a pair of screwdowns and driving mechanism therefor, and my invention further contemplates a unique combination of an unjamming device and such driving mechanism.

In many types of rolling mills, a pair of screwdowns are provided on top of each rolling mill stand in order to load the work and back-up rolls of the stand. Similar jamming occurs in a strip mill on occasion when the strip breaks and becomes wrapped two or more times around the work rolls of a given mill stand before the mill can be stopped.

In modern rolling mills the jamming forces which may be developed in the aforementioned and other situations are far beyond the capacities of conventional screwdown drive mechanisms. Therefore, an unjamming device is necessary to apply a very great force to the screwdowns through a very small angular displacement thereof. This displacement is sufiicient to remove at least the major portion of the jamming forces, so that subsequent adjustment of the screwdowns is within the capacity of the drive mechanism.

Because the screwdowns for a given mill stand are coupled to a common drive mechanism, it is essential that the screwdowns be unloaded simultaneously by the mill unjamming device. Preferably, the mill unjamming device operates through portions of the conventional screwdown drive mechanism to maximize the capacity of the unjamming device and also to ensure that those components of the drive mechanism which are directly engaged with the screwdowns or otherwise coupled thereto are likewise unjammed or unloaded when unjamming of the screwdowns is accomplished. Desirably, also the unjamming device is so coupled to the drive mechanism components that maximum torque can be applied to these components. By operation through selected components of the usual screwdown drive mechanism, the forces exerted by the unjamming devices are multiplied, without the use of separate and heavy linkages connected directly between the unjamming device and the screwdowns.

I am aware of a number of previous references which are of interest to the general subject of screwdown drive mechanisms. For the most part these references involve dual motive sources for the screwdown actuating linkages such that the screwdowns can be moved rapidly or slowly as desired for purposes of coarse and fine adjustments respectively. For example, the US. patent to Wheeler No. 2,961,901 discloses means for relieving pressures on sleeve type roll bearings through the provision of motive means coupled directly to the screwdowns so that the screwdowns can be moved quickly to prevent seizure of this type of bearing. However, the direct connection of the Wheeler screwdown adjustment with the screwdowns unnecessarily limits the applied torque. The Wheeler arrangement therefore is inappropriate for alleviating most jamming conditions.

In Burns No. 2,236,464 a single motive source can be operated alternatively through differing gearing paths for a relatively high speed coarse adjustment of the screwdowns and a relatively low speed fine adjustment thereof. A similar arrangement is found in Morgan No. 2,090,221 which provides a high ratio adjustment for the screwdowns under load and a low ratio or high speed, coarse adjustment for the screwdowns under no load.

Hodgson No. 669,242 and Wright No. 393,805 illustrate early types of rolling mills in which the screwdowns are adjusted manually. Cylinder operated means are provided for momentarily unloading the mill so that the manual adjustments can be made. As in the references discussed previously, the Hodgson and Wright motive means are incapable of supplying the tremendous unamming forces required in modern rolling mills.

In general, the high-speed, coarse adjustments or unloading devices of the prior art require direct connection to the screwdowns which in itself poses problems owing to space limitations of modern rolling mills. None of these devices permit the application of extremely large torques to the screwdowns through a very small angular displacement to eliminate jamming forces. Moreover, these high torque forces are not applied through drive mechanism components for further multiplication of the torque for unjamming purposes.

I overcome these disadvantages of the prior art by providing a mill unjamming device capable of being securely but momentarily engaged for application of extremely high torques to the screwdowns of a mill stand. The unjamming device is connected between operating components of a drive mechanism for the screwdowns so that the torques exerted by the unjamming device are further multiplied by those portions of the drive mechanism through which the jamming device is operative. A minimum of space and hardware is therefore required by my novel unjamming device, and in particular, separate mechanical connections between the unjamming device and the screwdowns are avoided. Most importantly, the screwdowns are operated simultaneously so as to avoid maximization of jamming forces at one or the other of the screwdowns or in related components of the drive mechanism. An equally important advantage stemming from the connection between the unjamming device and the drive mechanism is the simultaneous unjamming of related components of the drive mechanism so that the drive mechanism when restarted does not encounter unduly heavy loads.

I accomplish these desirable results by providing a driving mechanism for rolling mill screwdown means and the like, drive shaft means coupled to said screwdown means, first motive means coupled to said shaft means for rotating said screwdown means, and second motive means coupled to said shaft means for angular displacement to said shaft means, said second motive means including an actuating mechanism mounted entirely on said shaft means for effecting such angular displacement.

I also desirably provide a similar mill unjamming device wherein said shaft means include a pair of drive shafts coupled to screwdown means, and said actuating mechanism is disposed for applying equal and opposite angular displacements to said shafts.

I also desirably provide a similar mill unjamming device wherein mechanical advantage means are connected between said screwdown means and each of said shafts.

I also desirably provide a similar mill unjamming device wherein said screwdown means include a pair of spaced located screwdowns, said shaft means including a pair of shafts, each of said shafts is coupled to each of said screwdowns, and said second motive means are disposed intermediately of said screwdowns for substantially symmetrical application of second motive means forces to said screwdowns.

I also desirably provide a similar mill unjamming device wherein said second motive means includes latch and catch mechanisms mounted on said means, said catch member mechanism being secured to said shaft means for rotation therewith, said latch mechanism being rotatably mounted on said shaft means and adjacently of said catch mechanism, and actuating means coupled to said latch mechanism for angularly displacing said latch mechanism, said latch mechanism including means for engaging said catch mechanism for moving said catch mechanism and said shaft mean therewith.

I also desirably provide an unjamming mechanism for rolling mill screwdown means and the like, said mechanism comprising a pair of oppositely rotatable shafts coupled to said screw down means, shaft displacing means mounted upon each of said shafts for imparting equal and opposite angular displacements thereto, and motive means coupled between said shaft displacing means for actuating said displacing means in opposite directions.

I also desirably provide a similar mill unjamming device wherein said displacing means include a pair of catch members mounted respectively on said shafts for rotation therewith and a pair of latch mechanisms rotatabl mounted on said shafts and juxtaposed to said catch members respectively.

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same.

In the accompanying drawings I have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same, wherein:

FIG. 1 is a top plan view of a rolling mill stand showing upper screwdowns, a drive mechanism therefor, and one arrangement of my mill unjamming device;

FIG. 2 is a partial elevational view of thhe apparatus as shown in FIG. 1;

FIG. 3 is an enlarged, partial top plan view of the mill unjamming device of FIG. 1 including certain components of the drive mechanism associated therewith;

FIG. 4 is an elevational view, partially sectioned, of the apparatus as shown in FIG. 3; and

FIG. 5 is an enlarged, cross sectional view of the unjamming device as shown in FIG. 1 and taken along reference line VV thereof.

Referring now more particularly to FIGS. 1 and 2 of the drawings a rolling mill stand shown therein in cludes a pair of screwdown housings 12, 14 located atop the stand 10. Each of the screwdown housings 12, 14 communicates with a pair of worm casings 16 or 18, which together with their associated screwdown housing 12 or 14 enclose the upper portion of screw down 20 or 22, its associated worm gear 24, and a pair of worms 26, 27 or 28, 29.

The worms 26, 27, which are coupled to screwdown 20 are respectively mounted on a pair of drive shaft sections 30, '32 and rotated therewith by a pair of mill motors 34, 36 respectively. The motors 34, 36 are opposite in rotational direction so that the shafts 30, 32 are similarly driven for purposes described below. In furtherance of this purpose the worms 26, 27 are rightand left-hand pitched respectively.

The first drive shaft sections 30, 32, which are thus associated with the left screwdown 20 (as viewed in the drawings) are connected through couplings 38 to a pair of intermediate drive shaft sections 40, 42 and thence through a pair of clutches 44 to a third pair of drive shaft sections 46, 48 associated with the right screwdown 22. When the clutches 44 are engaged the latter drive shaft sections 46, 48 are oppositely rotated along with the first drive shaft sections 30, 32 and associated components. The worms 28, 29 associated with the second screwdown 22 are similarly rightand left-hand pitched for proper engagement and rotation of worm gear 24 and screwdown 22.

As better shown in FIG. 5 the clutches 44 are engaged and disengaged by operation of levers 50 which are pivoted at 52 to the top of the mill stand 10. This action, under control of actuating cylinders 54, advances and withdraws clutch components 56 in the conventional manner through link members 58. This permits rotation of the first screwdown 20 independently of the other screwdown 22, for example when it is necessary to place or restore the screwdowns to an in-step operation. Ordinarily, the clutches 44 are engaged and the mill motors 44, 4 6 apply balanced driving forces to each of the worm gears 24 and the screwdowns 20, 22 secured thereto.

A mill unjamming device 60 is mounted atop the mill stand 10 and generally between the upper screwdown housings 24. The unjamming device 60, instead of being connected directly to the screwdowns 20, 22 is coupled to and forms part of the drive mechanism for the screwdowns and specifically to oppositely rotated drive shafts 304046 and 324248 thereof. The unjamming device 60 is arranged so that very high torques can be exerted respectively upon the oppositely rotatable drive shafts. Preferably, the unjamming device is further arranged that the torques are equal and opposite in sense and are applied simultaneously to the drive shafts, which are oppositely rotated for this reason, as mentioned previously.

Through application of the unjamming torques in this manner to the drive shafts of the driving mechanism, the torques applied by the unjamming device 60 are multiplied by the mechanical advantage by the usual screwdown drive mechanism preferred, in this example includes the gearing (worms 26-29 and worms gears 24) associated with the screwdowns.

In consequence, the disclosed driving mechanism for the screwdowns 20, 22 is capable of rotating the screwdowns for adjustment purposes under ordinary mill loadings and is also capable of removing jamming forces en countered during the aforementioned accidental mill conditions. The driving mechanism for the screwdowns in effect, then, has two motive sources including the mill motors 34, 36 for normal screwdown operation and the unjamming device 60. The unjamming device 60 naturally is disengaged from the screwdown drive shafts, by means presently to be described, when the mill motors 34, 36 are operated. On the other hand, the mill jamming device 60 can be operated by merely de-energizing the mill motors 34, 36, without decoupling as the mill jamming device 60 applies only a small angular displacement to the screwdown drive shafts. On rare occasions. when the combined jamming forces associated with the screwdowns 20, 22 exceed the capacity of the unjamming device 60 or of the drive shafts and other associated components, the right screwdown 22 can be declutched, by operating cylinders 54, from the unjamming device 60 until the left screwdown 20 can be unjammed.

One arrangement of such mill unjamming device 60 is shown in FIGS. 1 and 2 and is described in greater detail in connection with FIGS. 3-5. The unjamming device 60 is coupled to the intermediate drive shaft sections 40, 42 which are oppositely rotated in this example as aforesaid. The unjamming device includes latch and catch mechanisms which are mounted on the intermediate shaft sections as detailed below. The latch mechanism includes a pair of latch housings 62, 64 which normally extend in an upright fashion from the top of the mill stand 10. The latch housings 62, 64 are rotatably mounted on the shaft extensions 40, 42 and are juxtaposed respectively to a pair of catch mechanisms including sprockets or rachet wheels 66, 68- (FIG. 4). Each of the catch members or ratchet wheels 66, 68 is secured to the associated intermediate drive shaft section 40 or 42 for rotation therewith. 4

Each of the latch housings 62, 64 is mounted at its lower end upon a pillow block type of bearing structure 70 which in turn is mounted on the associated shaft portion 40 or 42 for rotation relative thereto. As better shown in FIG. 5, each pillow block structure 70 generally straddles a stationary bearing structure 72 mounted on top of the mill housing for rotatably supporting the associated intermediate drive shaft portion 40 or 42. The associated catch or ratchet wheel 66 or 68 in turn is confined between components of the bearing structure 72. As mentioned previously and as set forth in greater detail in FIG. 5, each intermediate drive shaft portion 40 or 42 is connected to the remaining components of the screwdown drive shafts through the associated coupling 38 and clutch 44.

Motive means, for example, piston and cylinder arrangement 73, are connected between the latch housings 62, '64 (FIGS. 1, 3 and 4). Operation of the piston and cylinder 73 moves the latch housings 62, 64 in opposite directions to their chain outline positions 74, 76 respectively. The angular displacements 78, 80 must of necessity be equal and opposite owing to the connection of each screwdown drive shaft to the common worm gears 24 (FIG. 1).

Accordingly, each of the screwdowns 20, 22 are rotated through the same angular displacement to maintain an in-step movement of the screwdowns.

Before energizing the piston and cylinder arrangement 73 however, the latch housings 62, 64 are connected to the catch wheels 66, 68 respectively by moving latch elements 82, 84 (FIG. 4), into engagement with the catch or rachet wheels. This accomplished by slidably advancing the latch elements or plungers 82, 84 in their slide casings 86, 88 by means of an associated piston and cylinder arrangement 90 or other suitable motive means mounted on the latch housings 62, 64. In a particular embodiment of the invention the piston and cylinders 90 are pneumatically operated while the latch housing piston and cylinder 73 are hydraulically actuated owing to their obvious load differences. As evident from FIGS. 3 and 4 the slide casings 86, 88 are formed from latch housings side plates 92 with bracing plates 94, 96 extended therebetween. One of the bracing plates, for example the plate 96 of each slide casing, is provided with an aperture 98 through which actuating arm 100 of limit switch 102 is extended for the purposes of delimiting, through suitable circuitry (not shown), the movements of the latch plungers 82, 84.

Movements of the latch housing cylinder arrangement 73 are similarly delimited by a pair of limit switches 104, 106 which are mounted in this example on an exterior surface of the cylinder for movement therewith. On the other hand, a switch-operating arm 108 is secured to piston rod 110 and the associated latch housing 64 for movement therewith. The piston and cylinder arrange ment 73 is controlled therefore by relative displacements between its components rather than by the absolute displacements of one of its components.

In operation, upon occurrence of a jamming condition, the mill motors 34, 36 are immediately de-energized for example by internal overload protective circuitry or by suitable overload sensing devices (not shown) coupled to the rolling mill. To eliminate the jamming forces, the

unjamming device 60 (FIG. 1) is coupled to the drive mechanism drive shafts by actuating latch element cylinders 90 of the unjamming device. Upon engagement of the latch plungers 82, 84 with the respective catch or rachet wheels 66, 68, the unjamming device becomes mechanically coupled to the intermediate drive shaft portions 40, '42. The latch housing cylinder 73 is then energized to displace angularly the latch housings 62, 64 from their solid outline positions (FIG. 4) to their chain outline positions 74, 76 respectively. The angular displacement of the latch housings 62, 64, and the attendant angular displacements of the screwdown drive shafts, are equal and opposite in every case as the drive shafts are in effect coupled together through worm gears 24 and worms 26-29. Except in unusual situations, the clutches 44 are not disengaged.

Extremely high torques are thus applied to the intermediate drive shaft portions 40, 42 and the associated components owing to the rotatable mounting of the latch housings 62, 64 directly upon the drive shaft portions 40, 42 respectively. Thus, the driving moment arm of each latch housing 62 or '64 is substantially the same length as the driven moment arm. of the associated catch element or rachet wheel 66 or 68 owing to the common or concentric mounting of the rachet wheel and the latch housing on the associated drive shaft portion 40 or 42. Obviously, the driving moment arm of the latch housings 62, 64 would be considerably lengthened if the latch housings were pivoted at a more remote location, and a mechanical disadvantage would be introduced. The driven moment arms of the latch housings 62, 64 which arms desirably are identical in length, can be lengthened or shortened depending upon the particular locations of the pivoted connections 112, 114 of the latch housings 62, 64 with the cylinder arrangement 73.

From the foregoing it will be apparent that novel and efficient forms of mill unjamming devices have been described herein. While I have shown and described certain presently preferred embodiments of the invention and have illustrated presently preferred methods of practic ing the same, it is to be distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the spirit and scope of the invention.

I claim:

1. A driving mechanism for rolling mill screwdown means and the like, drive shaft means coupled to said screwdown means, relatively low torque first motive means coupled to said shaft means for rotating said screwdown means, and relatively high torque second motive means coupled to said shaft means for imparting a relatively small angular displacement through said shaft means to said screwdown means and to said first motive means, said second motive means including an actuating mechanism mounted entirely on said shaft means for effecting such angular displacement.

2. The combination according to claim 1 wherein said shaft means include a pair of drive shafts coupled to screwdown means, and said actuating mechanism is disposed for applying equal and opposite angular displacements to said shafts.

3. The combination according to claim 1 wherein said screwdown means include a pair of spacedly located screwdowns, said shaft means include a pair of shafts, each of said shafts is coupled to each of said screwdowns, and said second motive means are disposed intermediately of said screwdowns for substantially symmetrical application of second motive means forces to said screwdowns.

4. The combination according to claim 2 wherein clutch means are disposed in each of said drive shafts at a location generally between said second motive means and one of said screwdowns, and means are provided for 5. A driving mechanism for rolling mill screwdown means and the like, drive shaft means coupled to said screwdown means, first motive means coupled to said shaft means for rotating said screwdown means, second motive means coupled to said shaft means for imparting a relatively small angular displacement to said shaft means, said second motive means including an actuating mechanism mounted entirely on said shaft means for effecting such angular displacement, said second motive means including latch and catch mechanisms mounted on said shaft means, said catch mechanism being secured to said shaft means for rotation therewith, said latch mechanism being rotatably mounted on said shaft means and adjacently of said catch mechanism, and actuating means coupled to said latch mechanism for angularly displacing said latch mechanism, said latch mechanism including means for engaging said catch mechanism for moving said catch mechanism and said shaft means therewith.

6. The combination according to claim wherein said actuating means include a piston and cylinder arrangement connected respectively to said latch and catch mechanisms.

7. The combination according to claim 5 wherein said latch mechanism includes a latch housing rotatably mounted on said drive shaft means, a latch element slidably mounted on said latch housing, and means on said housing for moving said latch member into engagement with said catch mechanism.

8. The combination according to claim 6 wherein said latch and catch mechanism is positioned by bearing means forming part of a support structure for said shaft means.

9. An unjamming mechanism for rolling mill screwdown means and the like, said mechanism comprising a pair of oppositely rotatable shafts coupled to said screwdown means, relatively low torque first motive means coupled to said shafts, shaft displacing means mounted upon each of said shafts for imparting substantially equal and opposite relatively small angular displacements thereto, and relatively high torque second motive means coupled between said shaft displacing means for actuating said displacing means in opposite directions to effect said displacements.

10. An unjamming mechanism for rolling mill screwdown means and the like, said mechanism comprising a pair of oppositely rotatable shafts coupled to said screwdown means, shaft displacing means mounted on each of said shafts for imparting equal and opposite angular displacements thereto, motive means coupled between said shaft displacing means for actuating said displacing means in opposite directions, said displacing means including a pair of catch members mounted respectively on said shafts for rotation therewith and a pair of latch mechanisms rotatably mounted on said shafts and juxtaposed to said catch members respectively.

11. The combination according to claim 10 wherein said latch mechanisms each include a movable latch element, means for mounting said latch element for movement toward and away from a position of engagement with the associated one of said catch members and means for moving said latch element.

12. The combination according to claim 10 wherein motive means are coupled between said latch mechanisms for common angular displacement thereof.

13. The combination according to claim 12 wherein said motive means include a piston and cylinder arrangement connected respectively to said latch mechanisms.

14. The combination according to claim 13 wherein cooperating limit switch means are mounted on one of said piston and said cylinder for movement therewith, switch operating means are mounted on the other of said piston and said cylinder for movement therewith for delimiting the relative movement of said piston and said cylinder.

15. The combination according to claim 1 wherein said second motive means are mounted entirely on said shaft means and are coupled thereto.

16. The combination according to claim 9 wherein said second motive means are mounted entirely on said shaft displacing means.

17. A driving mechanism for rolling mill screwdown means and the like, driveshaft means coupled to said screwdown means, first motive means coupled to said shaft means for rotating said screwdown means, second motive means coupled to said shaft means for imparting a relatively small angular displacement to said shaft means, said second motive means including an actuating mechanism mounted entirely on said shaft means for effecting such angular displacement, said second motive means including at least one catch member mounted on said shaft means for rotation therewith, and a latch mechanism rotatably mounted on said shaft means and adjacently of said catch member, and means for selectively coupling said latch mechanism to said catch member and to said actuating mechanism to move said catch member and said shaft means therewith when so coupled.

References Cited UNITED STATES PATENTS.

1,537,240 5/1925 Lewis 72248 1,576,266 3/192'6 Biggert, Jr. 72-248 669,242 3/1901 Hodgson 72247 313,206 3/1885 Hemphill 72248 1,825,957 10/1931 Johnson 72248 2,236,464 3/1941 Burns 72248 2,684,001 7/1954 Wilson 72248 3,104,567 9/ 1963 Sieger 72248 3,147,650 9/1964 Allen 72248 CHARLES W. LANHAM, Primary Examiner M. J. KEENAN, Assistant Examiner 

